Method for preparing aluminum film on surface of wafer through physical vapor deposition

Abstract

The invention belongs to the field of semiconductor technologies, and provides a method for preparing an aluminum film on the surface of a wafer through physical vapor deposition, and in the physical vapor deposition, the deposition power is limited to be 1500-2500 W and / or the flow of argon is 30-40 sccm. The method can reduce the size of crystal lattices on the surface of the aluminum film, no crystal lattice residual mark exists on the surface after dry etching, and the surface defect phenomenon is improved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor processes and relates to a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition. Background Art

[0002] With the development of semiconductor integrated circuit manufacturing technology, the requirements for physical vapor deposition (PVD) processes are getting higher and higher. Especially in the manufacture of power devices, the PVD process is used to deposit a thin film of a metal material on the surface of a wafer, such as an aluminum-copper thin film containing silicon. In subsequent processes, the wafer deposited with the aluminum-copper material thin film will undergo a dry etching process to remove unnecessary patterns. Therefore, in the PVD process, it is necessary to ensure the lattice quality of the aluminum-copper material thin film on the wafer so that the lattice of the aluminum-copper material thin film on the chip after dry etching is defect-free, thereby making the performance of the chip consistent and improving the yield of the chip. Therefore, in the PVD process, how to improve the lattice is one of the main problems faced by this field. Summary of the Invention

[0003] To solve the technical problems existing in the prior art, the present invention provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition. This method can reduce the lattice size on the surface of the aluminum thin film, and there is no lattice residue mark on the surface after dry etching, improving the surface defect phenomenon.

[0004] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition. This method includes the following steps:

[0006] (1) Provide a wafer;

[0007] (2) Prepare an aluminum thin film on the surface of the wafer by the physical vapor deposition. In the physical vapor deposition, the deposition power is limited to 1500 - 2500 W and / or the flow rate of argon gas on the front side is 30 - 40 sccm;

[0008] (3) Perform an annealing treatment.

[0009] As a preferred technical solution of the present invention, the temperature of the physical vapor deposition is 430 - 480 °C.

[0010] As a preferred technical solution of the present invention, the flow rate of ArH in the physical vapor deposition is 5 - 15 sccm.

[0011] As a preferred technical solution of the present invention, the reflux treatment time of the physical vapor deposition is 40 - 200 s.

[0012] As a preferred technical solution of the present invention, the number of cycles of the physical vapor deposition is 5 - 10 times.

[0013] As a preferred technical solution of the present invention, the average grain size of the aluminum thin film is 7.0 - 9.0 μm.

[0014] As a preferred technical solution of the present invention, the maximum grain size at the middle of the aluminum thin film is not greater than 55 μm, and the maximum grain size at the edge is not greater than 65 μm.

[0015] As a preferred technical solution of the present invention, the method for preparing the aluminum thin film on the wafer surface by physical vapor deposition includes: in physical vapor deposition, the deposition power is limited to 1500 - 2500 W, the flow rate of argon on the front side is 10 - 15 sccm, the temperature is 430 - 480 °C, the flow rate of ArH is 5 - 15 sccm, the reflux treatment time is 40 - 200 s, and the number of cycles is 5 - 10 times; the maximum grain size at the middle of the aluminum thin film is not greater than 55 μm, and the maximum grain size at the edge is not greater than 65 μm.

[0016] As a preferred technical solution of the present invention, the method for preparing the aluminum thin film on the wafer surface by physical vapor deposition includes: in physical vapor deposition, the deposition power is limited to 500 - 1000 W, the flow rate of argon on the front side is 30 - 40 sccm, the temperature is 430 - 480 °C, the flow rate of ArH is 5 - 15 sccm, the reflux treatment time is 40 - 200 s, and the number of cycles is 5 - 10 times; the maximum grain size at the middle of the aluminum thin film is not greater than 55 μm, and the maximum grain size at the edge is not greater than 65 μm.

[0017] As a preferred technical solution of the present invention, the method for preparing the aluminum thin film on the wafer surface by physical vapor deposition includes: in physical vapor deposition, the deposition power is limited to 1500 - 2500 W, the flow rate of argon on the front side is 30 - 40 sccm, the temperature is 430 - 480 °C, the flow rate of ArH is 5 - 15 sccm, the reflux treatment time is 40 - 200 s, and the number of cycles is 5 - 10 times; the maximum grain size at the middle of the aluminum thin film is not greater than 55 μm, and the maximum grain size at the edge is not greater than 65 μm.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The present invention provides a method for preparing an aluminum thin film on the wafer surface by physical vapor deposition. Through the coordinated optimization of the deposition power, the flow rate of argon on the front side, and the annealing time, the lattice size on the surface of the aluminum thin film can be reduced, and there is no lattice residue imprint on the surface after dry etching, improving the surface defects. Description of the Drawings

[0020] Figure 1a It is a microscopic grain diagram of the aluminum thin film prepared in Example 1.

[0021] Figure 1b Microscopic grain map of the aluminum thin film prepared in Example 6.

[0022] Figure 1c Microscopic grain map of the aluminum thin film prepared in Comparative Example 1.

[0023] Figure 1d Microscopic grain map of the aluminum thin film prepared in Comparative Example 2.

[0024] Figure 1e Microscopic grain map of the aluminum thin film prepared in Comparative Example 3.

[0025] Figure 2a Surface effect diagram of the etched aluminum thin film prepared in Example 1.

[0026] Figure 2b Surface effect diagram of the etched aluminum thin film prepared in Example 6.

[0027] Figure 2c Surface effect diagram of the etched aluminum thin film prepared in Comparative Example 1.

[0028] Figure 2d Surface effect diagram of the etched aluminum thin film prepared in Comparative Example 2.

[0029] Figure 2e Surface effect diagram of the etched aluminum thin film prepared in Comparative Example 3.

[0030] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed implementation manners

[0031] The technical solution of the present application will be further described below through specific implementation manners.

[0032] The present invention provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition,

[0033] The method includes the following steps:

[0034] (1) Provide a wafer;

[0035] (2) Prepare an aluminum thin film on the surface of the wafer by the physical vapor deposition, and in the physical vapor deposition, the deposition power is limited to 1500-2500 W and / or the flow rate of argon on the front side is 30-40 sccm;

[0036] (3) Perform an annealing treatment.

[0037] Among them, the deposition power can be 1500 W, 1600 W, 1700 W, 1800 W, 1900 W, 2000 W, 2100 W, 2200 W, 2300 W, 2400 W or 2500 W, etc., and the flow rate of argon on the front side can be 30 sccm, 31 sccm, 32 sccm, 33 sccm, 34 sccm, 35 sccm, 36 sccm, 37 sccm, 38 sccm, 39 sccm or 40 sccm, etc., but it is not limited to the listed values, and other unlisted values within the above numerical ranges are equally applicable.

[0038] For the existing process, the best-known method for depositing aluminum thin films is a deposition power of 800 W, an argon flow rate of 12 sccm, and an ArH flow rate of 7 sccm. However, surface lattice defects will appear on the aluminum thin films prepared by this process after dry etching. By adjusting the deposition power and / or the flow rate of argon, the present invention finds that by optimizing the above parameters, the surface lattice particle size of the aluminum thin film can be reduced, so that there is no lattice imprint on the aluminum thin film after dry etching, and the chip yield is improved.

[0039] In a specific embodiment of the present invention, the material of the wafer can be any wafer material commonly used in the semiconductor field, such as single crystal silicon, SOI or SiGe, etc.

[0040] In a specific embodiment of the present invention, the target used for physical vapor deposition can be a high-purity copper target, such as 5N grade, 5N5 grade and 6N grade, etc.

[0041] In a specific embodiment of the present invention, the temperature of physical vapor deposition is 430 - 480 °C, such as 430 °C, 435 °C, 440 °C, 445 °C, 450 °C, 455 °C, 460 °C, 465 °C, 470 °C, 475 °C or 480 °C, etc., but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0042] In a specific embodiment of the present invention, the ArH flow rate of physical vapor deposition is 5 - 15 sccm, such as 5 sccm, 6 sccm, 7 sccm, 8 sccm, 9 sccm, 10 sccm, 11 sccm, 12 sccm, 13 sccm, 14 sccm or 15 sccm, etc., but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0043] In a specific embodiment of the present invention, the front-side argon flow rate refers to the argon flow rate introduced on the front side of the wafer as a plasma solid. The ArH flow rate refers to the argon flow rate introduced on the back side of the wafer.

[0044] In a specific embodiment of the present invention, the reflux treatment time of physical vapor deposition is 40 to 200 s, such as 40 s, 50 s, 60 s, 80 s, 100 s, 120 s, 150 s, 180 s or 200 s, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0045] In a specific embodiment of the present invention, the reflux treatment means that argon is introduced into the back side of the wafer, and argon is stopped from being introduced into the front side of the wafer. The argon on the back side provides heat transfer to make the hot Al flow.

[0046] In a specific embodiment of the present invention, the number of cycles of physical vapor deposition is 5 to 10 times, such as 5 times, 6 times, 7 times, 8 times, 9 times or 10 times, etc.

[0047] In a specific embodiment of the present invention, the number of cycles of physical vapor deposition refers to the number of times of repeating the deposition and annealing of the aluminum thin film.

[0048] In a specific embodiment of the present invention, the average grain size of the aluminum thin film is 7.0 to 9.0 μm, such as 7.0μm, 7.2μm, 7.5μm, 7.8μm, 8.0μm, 8.2μm, 8.5μm, 8.8μm or 9.0μm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0049] In a specific embodiment of the present invention, the maximum grain size at the middle of the aluminum thin film is not greater than 55μm, and the maximum grain size at the edge is not greater than 65μm., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0050] In a specific embodiment of the present invention, the thickness of the aluminum thin film can be adjusted according to the preparation requirements and will not be further limited here.

[0051] In a specific embodiment of the present invention, the method for preparing the aluminum thin film on the wafer surface by physical vapor deposition includes: in physical vapor deposition, the deposition power is limited to 1500 to 2500 W, the flow rate of argon is 10 to 15 sccm, the temperature is 430 to 480 °C, the flow rate of ArH is 5 to 15 sccm, the reflux treatment time is 40 to 200 s, and the number of cycles is 5 to 10 times; the maximum grain size at the middle of the aluminum thin film is not greater than 55μm, and the maximum grain size at the edge is not greater than 65μm.

[0052] In a specific embodiment of the present invention, the method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition includes: in physical vapor deposition, the deposition power is limited to 500-1000 W, the flow rate of argon is 30-40 sccm, the temperature is 430-480 °C, the flow rate of ArH is 5-15 sccm, the reflux treatment time is 40-200 s, and the number of cycles is 5-10 times; the maximum grain size at the middle of the aluminum thin film is not greater than 55 μm, and the maximum grain size at the edge is not greater than 65 μm.

[0053] In a specific embodiment of the present invention, the method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition includes: in physical vapor deposition, the deposition power is limited to 1500-2500 W, the flow rate of argon is 30-40 sccm, the temperature is 430-480 °C, the flow rate of ArH is 5-15 sccm, the reflux treatment time is 40-200 s, and the number of cycles is 5-10 times; the maximum grain size at the middle of the aluminum thin film is not greater than 55 μm, and the maximum grain size at the edge is not greater than 65 μm.

[0054] In a specific embodiment of the present invention, the annealing treatment temperature is 100-200 °C and the time is 10-20 s. Among them, the temperature can be 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C or 200 °C, etc., and the time can be 10 s, 11 s, 12 s, 13 s, 14 s, 15 s, 16 s, 17 s, 18 s, 19 s or 20 s, etc., but is not limited to the listed values. Other unlisted values within the above numerical ranges are equally applicable.

[0055] To better illustrate the present invention and facilitate understanding of its technical solution, the typical but non-limiting embodiments of the present invention are as follows:

[0056] Example 1

[0057] This example provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0058] In physical vapor deposition, the deposition power is limited to 2000 W, the flow rate of argon on the front side is 12 sccm, the temperature is 460 °C, the flow rate of ArH is 7 sccm, and the reflux treatment time is 60 s; the annealing treatment temperature is 150 °C and the time is 15 s; the number of cycles is 7 times.

[0059] Example 2

[0060] Except that the flow rate of argon is 10 sccm, the other conditions in this example are the same as those in Example 1.

[0061] Example 3

[0062] In this embodiment, except that the flow rate of argon is 15 sccm, the other conditions are the same as those in Embodiment 1.

[0063] Embodiment 4

[0064] In this embodiment, except that the deposition power is 1500 w, the other conditions are the same as those in Embodiment 1.

[0065] Embodiment 5

[0066] In this embodiment, except that the deposition power is 2500 w, the other conditions are the same as those in Embodiment 1.

[0067] Embodiment 6

[0068] This embodiment provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0069] In physical vapor deposition, the deposition power is limited to 800 W, the flow rate of argon on the front side is 35 sccm, the temperature is 460 °C, the flow rate of ArH is 7 sccm, the reflux treatment time is 60 s; the annealing treatment temperature is 150 °C, and the time is 15 s; the number of cycles is 7 times.

[0070] Embodiment 7

[0071] In this embodiment, except that the flow rate of argon is 30 sccm, the other conditions are the same as those in Embodiment 1.

[0072] Embodiment 8

[0073] In this embodiment, except that the flow rate of argon is 40 sccm, the other conditions are the same as those in Embodiment 1.

[0074] Embodiment 9

[0075] In this embodiment, except that the deposition power is 500 w, the other conditions are the same as those in Embodiment 1.

[0076] Embodiment 10

[0077] In this embodiment, except that the deposition power is 1000 w, the other conditions are the same as those in Embodiment 1.

[0078] Embodiment 11

[0079] This embodiment provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0080] In physical vapor deposition, the deposition power is defined as 2000 W, the flow rate of argon on the front side is 35 sccm, the temperature is 440 °C, the ArH flow rate is 15 sccm, the reflux treatment time is 200 s; the annealing treatment temperature is 100 °C and the time is 20 s; the number of cycles is 5 times.

[0081] Example 12

[0082] This example provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0083] In physical vapor deposition, the deposition power is defined as 2000 W, the flow rate of argon on the front side is 35 sccm, the temperature is 480 °C, the ArH flow rate is 5 sccm, the reflux treatment time is 40 s; the annealing treatment temperature is 200 °C and the time is 10 s; the number of cycles is 10 times.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0086] In physical vapor deposition, the deposition power is defined as 800 W, the flow rate of argon on the front side is 12 sccm, the temperature is 460 °C, the ArH flow rate is 7 sccm, the reflux treatment time is 60 s, and the number of cycles is 7 times.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0089] In physical vapor deposition, the deposition power is defined as 800 W, the flow rate of argon on the front side is 12 sccm, the temperature is 460 °C, the ArH flow rate is 7 sccm, the reflux treatment time is 200 s, and the number of cycles is 7 times.

[0090] Comparative Example 3

[0091] This comparative example provides a method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, and the method includes:

[0092] In physical vapor deposition, the deposition power is defined as 800 W, the flow rate of argon on the front side is 12 sccm, the temperature is 460 °C, the ArH flow rate is 15 sccm, the reflux treatment time is 60 s, and the number of cycles is 10 times.

[0093] The wafers used in Examples 1 - 12 and Comparative Examples 1 - 3 are single - crystal silicon wafers, the target material is a high - purity aluminum target (6N), and the thickness of the prepared aluminum thin film is 4 μm.

[0094] The surface grain boundary characteristics and grain size of the aluminum thin films prepared in Example 1, Example 6, and Comparative Examples 1-3 were tested using electron backscatter diffraction (EBSD), and the results are shown in Table 1.

[0095] Table 1

[0096]

[0097] The surface grain size of the aluminum thin films prepared in Examples 1-12 and Comparative Examples 1-3 was tested using electron backscatter diffraction (EBSD). Meanwhile, the aluminum thin films were dry-etched, and it was determined whether there were lattice imprints on the surface. If there were no lattice imprints, it was marked as OK; if there were lattice imprints, it was marked as NG. The results are shown in Table 2.

[0098] The method of dry etching was as follows: BCl3 and Cl2 were introduced to dry-etch the aluminum thin films. The flow rate of BCl3 was approximately 100 sccm, the flow rate of Cl2 was 100 sccm, the power of the power supply was 600 w, and the substrate bias voltage was 50 w.

[0099] The criterion for determining whether there were lattice imprints on the surface was to check for lattice imprints under an optical microscope.

[0100] Table 2

[0101]

[0102] From the results of Table 1, Table 2, and Figure 1a -e and Figure 2a -e, it can be seen that for the method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition provided by the present invention, by adjusting the deposition power and / or the flow rate of argon, the lattice grain size on the surface of the aluminum thin film can be reduced, and thus there are no lattice imprints on the aluminum thin film after dry etching. In Comparative Example 1, a conventional method for depositing an aluminum thin film by PVD was used, and the obtained aluminum thin film had a relatively large grain size, and obvious lattice imprints appeared after dry etching; in Comparative Example 2, the reflux treatment time was increased, but it had no effect on the grain size, and the problem of lattice imprints after dry etching was not improved; in Comparative Example 3, increasing the ArH flow rate also had no effect on the grain size, and lattice imprint problems still occurred after dry etching.

[0103] The present invention uses the above-mentioned examples to illustrate the detailed structural features of the present invention. However, the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0104] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0105] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination manners.

[0106] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition, characterized in that, The method includes the following steps: (1) Provide a wafer; (2) Prepare an aluminum thin film on the surface of the wafer by physical vapor deposition, wherein the deposition power in the physical vapor deposition is defined as 1500 - 2500 W and / or the flow rate of argon gas on the front side is 30 - 40 sccm; (3) Perform annealing treatment.

2. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claim 1, wherein, The temperature of the physical vapor deposition is 430 - 480 °C.

3. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claim 1, characterized in that, The flow rate of ArH in the physical vapor deposition is 5 - 15 sccm.

4. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claim 1, wherein The reflux treatment time of the physical vapor deposition is 40 - 200 s.

5. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claim 1, wherein The number of cycles of the physical vapor deposition is 5 - 10 times.

6. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claim 1, characterized in that, The average grain size of the aluminum thin film is 7.0 - 9.0 μm.

7. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claim 1, characterized in that, The maximum grain size at the middle of the aluminum thin film is not more than 55 μm, and the maximum grain size at the edge is not more than 65 μm.

8. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claims 1 to 7, characterized in that, In the physical vapor deposition, the deposition power is defined as 1500 - 2500 W, the flow rate of argon gas on the front side is 10 - 15 sccm, the temperature is 430 - 480 °C, the flow rate of ArH is 5 - 15 sccm, the reflux treatment time is 40 - 200 s, and the number of cycles is 5 - 10 times; the maximum grain size at the middle of the aluminum thin film is not more than 55 μm, and the maximum grain size at the edge is not more than 65 μm.

9. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claims 1 to 7, characterized in that, In the physical vapor deposition, the deposition power is defined as 500 - 1000 W, the flow rate of argon gas on the front side is 30 - 40 sccm, the temperature is 430 - 480 °C, the flow rate of ArH is 5 - 15 sccm, the reflux treatment time is 40 - 200 s, and the number of cycles is 5 - 10 times; the maximum grain size at the middle of the aluminum thin film is not more than 55 μm, and the maximum grain size at the edge is not more than 65 μm.

10. The method for preparing an aluminum thin film on the surface of a wafer by physical vapor deposition according to claims 1 to 7, characterized in that, In the physical vapor deposition, the deposition power is defined as 1500 - 2500 W, the flow rate of argon gas on the front side is 30 - 40 sccm, the temperature is 430 - 480 °C, the flow rate of ArH is 5 - 15 sccm, the reflux treatment time is 40 - 200 s, and the number of cycles is 5 - 10 times; the maximum grain size at the middle of the aluminum thin film is not more than 55 μm, and the maximum grain size at the edge is not more than 65 μm.

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